In January 1941, the weekly magazine, Picture Post, published a special issue in which some of the foremost social thinkers of the day set out their visions for the reconstruction of postwar Britain. To illustrate the theme of planning for the future, the cover of the magazine carried a photograph of six tousle-haired toddlers squatting entirely naked on a water chute.

It is an arresting image which, even in black and white and after the passage of 60 years, summons up the beguiling innocence of childhood. But in our cynical age, one cannot look at it without also sensing something darker and more disturbing just out of frame: the shadow of the paedophile who has forced society to place boundaries around our children. These boundaries are becoming more and more like prisons, which stifle development rather than foster it. Sixty years from now, will sociologists look back and say that the biggest threat came from paedophilia - or from paranoia?

Frank Furedi, professor of sociology at Kent University, can afford to say, "I told you so." His book, Paranoid Parenting, is a well-argued critique of our increasingly risk-free society, which tries to hermetically seal children from every conceivable "threat". He is not at all surprised by the decision of the Edinburgh authorities, reported this week, to issue an edict about the use of videos or cameras at school and nursery activities in case the footage falls into the wrong hands.

"It is important to realise that this is not some maverick decision," he says. "Within the teaching and local education world, there is a phenomenally strong climate of watching your back and taking steps to ward off the threat of being blamed, or worse, sued, for not foreseeing a risk. When it comes to child protection, we now regard almost every aspect of children's lives from the paedophile's point of view, so that even the most innocent activities - like taping a nativity play - have a sinister connotation."

A spokesman for Edinburgh city council defended its decision on the grounds that, in both Scotland and England, paedophiles have been found with video footage taken at school plays. If this is the case, it has escaped the attention of Jim Reynolds, the first head of the Metropolitan Police Paedophilia Unit and now a consultant on child protection. "I think this is a total overreaction. I have no knowledge of videos or photos taken at school events being used in relation to child pornography. This is a new one on me."

He concedes, however, that images captured without the knowledge of the child or its parents do turn up in the collections of paedophiles.

"One of the men I investigated had taken a series of photos from a seaside esplanade overlooking a beach." he says. "They were the kind of scene you would routinely find on any beach. Mums and dads holding towels around their youngsters while they climbed out of wet trunks. This is what I would class as erotica. In other words, it turned this guy on, but the images were not pornographic and he couldn't possibly be prosecuted for having them. However, if someone has dozens of such photos, it is a pretty good pointer to other behaviour that goes with being paedophile."

It is also a fact that some predatory paedophiles take photos of children to whom they are attracted, in the street or in parks, as a first step towards making an approach and "grooming" them for sex. But in the present climate, it is all too easy to jump to conclusions - as is conceded by Dee Warner, co-founder of the campaigning group, Mothers Against Murder, Manslaughter and Aggression (Mamma), recalls being part of a group of parents who confronted a young man taking photographs of young children enjoying a paddling pool near her home in south London. "Our first thought was that this chap was up to no good and we were all ready to do battle to protect our kids. As it happened, he was from the local paper on a story. But you can't be too careful these days."

Mamma has added its voice to protests against high-risk paedophiles being released from prison and the siting of treatment centres for sex offenders in residential areas, leading some to see it as contributing to the state of public paranoia. But Dee Warner makes a distinction between raising awareness of the issue and over-reacting. "I think the Edinburgh council decision is completely over the top. We are letting paedophiles rule our lives when this sort of thing happens."

This view is echoed by the deputy head of a school in Essex which is quite happy to allow parents and relatives to bring camcorders into the Christmas carol concert. "We had a staffroom discussion about the Edinburgh decision - and those of some other schools to ban filming - and opinion was unanimous that it was daft.

"It also highlights the double standards of our society. At many local authority swimming pools, it is now prohibited to take still or moving pictures, yet the last time I took my two children to Center Parcs, cameras for use underwater were on sale."

Perhaps this issue of double standards is the most pertinent one. Never before have children been so overtly sexualised - in the cosmetics, fashion and music industries, for example - and yet never before have we been so fearful of those who would prey on them. For those who defend this dichotomy, the answer is that context is everything. But then we find ourselves on very slippery conceptual ground. When the Saatchi Gallery mounted an exhibition in 2001 and included a photograph taken by Tierney Gearon of her two young children naked on a beach, wearing animal masks, there was a media furore, with the Daily Mail suggesting that it was "encouraging evil". Yet in reporting the Edinburgh issue, the Mail, barometer of Middle England, reached instinctively for the stick with which it likes to beat liberal opinion and called the decision "political correctness gone bonkers".

Frank Furedi thinks the battle to distinguish real from imagined danger has already been lost and that, if Britain follows the example of the US, there will be many more "Edinburgh decisions". "I was in California recently, where the message of one so-called child protection expert was that 'Every adult you don't know is a potential paedophile'," he says. "And in a San Francisco park, I saw a sign reading, 'Unaccompanied adults not allowed.' It used to be children who had to be accompanied - now it's the adults." The phenomenon is already well on its way: 18 months ago, British Airways instructed its in-flight staff to ensure that male passengers should not be allowed to sit next to a child travelling alone, after one case of inappropriate behaviour had come to light.

The child protection agencies, the NSPCC and Barnardos, have both criticised the ban on school photos and camcorders because they believe milestones in children's lives should be marked and treasured. But no one has really grasped the core of the issue, which is that, while we are unceasingly on patrol against the "stranger danger" that supposedly stalks our children, we remain dangerously complacent about the child sex abuse that is taking place right now in some of those families who have been attending carol concerts and preparing to celebrate Christmas. Despite the enduring appeal of the nativity story, that may be the most important message to be learned at this time of the year.